Mr. Rubio’s inability to do anything besides repeat canned talking points was startling. Worse, it was funny, which means that it has gone viral. And it reinforced the narrative that he is nothing but an empty suit. But really, isn’t everyone in his party doing pretty much the same thing, if not so conspicuously?

Krugman lists the canned talking points delivered, and evidently believed, by all the GOP candidates.

First, there’s the ritual denunciation of Obamacare as a terrible, very bad, no good, job-killing law.

Then there’s the assertion that taxing the rich has terrible effects on economic growth, and conversely that tax cuts at the top can be counted on to produce an economic miracle.

... on foreign policy the required G.O.P. position has become one of utter confidence in the effectiveness of military force.

Like her or not, Hillary Clinton is a genuine policy wonk, who can think on her feet and clearly knows what she is talking about on many issues. Bernie Sanders is much more of a one-note candidate, but at least his signature issue — rising inequality and the effects of money on politics — reflects real concerns. When you revisit Democratic debates after what went down Saturday, it doesn’t feel as if you’re watching a different party, it feels as if you’ve entered a different intellectual and moral universe.

So how did this happen to the G.O.P.? In a direct sense, I suspect that it has a lot to do with Foxification, the way Republican primary voters live in a media bubble into which awkward facts can’t penetrate. But there must be deeper causes behind the creation of that bubble.

Whatever the ultimate reason, however, the point is that while Mr. Rubio did indeed make a fool of himself on Saturday, he wasn’t the only person on that stage spouting canned talking points that are divorced from reality. They all were, even if the other candidates managed to avoid repeating themselves word for word.